What should the summary of efficacy data include to support conclusions about a treatment's effect?

• A. Randomization scheme
• B. The study sponsor's financial details
• C. The marketing plan
• D. Effect sizes and confidence intervals for primary and key secondary endpoints

Answer: (D)

Understanding how efficacy is summarized hinges on showing both how big the treatment effect is and how precisely that effect is estimated. The best summary reports the effect sizes for the primary outcome and the most important secondary outcomes, along with confidence intervals. The effect size tells you the magnitude of the difference between the treatment and control (for example, risk difference, relative risk, odds ratio, mean difference, or hazard ratio), while the confidence interval provides a range of values within which the true effect likely lies and indicates the precision of the estimate. A narrow confidence interval that excludes no effect supports a more confident conclusion about a real treatment effect, whereas a wide interval or one that includes no effect signals uncertainty.

Items like the randomization scheme, the sponsor’s financial details, or the marketing plan are not part of the efficacy data summary used to support conclusions about the treatment’s effect. They pertain to study design, sponsorship, or commercialization rather than the reported magnitude and precision of efficacy outcomes.